我的程序为什么总是Running?

#include "stdio.h"

#include "string.h"

int main()

{

int a[6000],len,i,s;

char x[6000];

while(1)

{

i=1;

gets(x);

len=strlen(x);

if(len==1&&x[0]=='0') return 0;

a[1]=1;

if(x[2]=='0') a[2]=1;

else if((x[0]=='1'||x[0]=='2')&&(x[1]=='1'||x[1]=='2'||x[1]=='3'||x[1]=='4'||x[1]=='5'||x[1]=='6'))

a[2]=2;

else a[2]=1;

for(i=3;i